"Consumers don't fully understand the benefit of low rolling resistant tires. They believe they are forfeiting important aspects of tire performance by opting for low rolling resistant tires, yet don't know how much improvement in fuel efficiency they should expect in return."

Exactly. The consumers are right, by the way. They are either paying more for a LRR tire, or they are accepting a tradeoff in braking performance, ride, noise, life and robustness in return for an unknown improvement in mpg which they might achieve by blowing some nicer tires up a bit.

I was gently nulling over your jibe about clever people defining tests. There is one cracker of an example. The standard EEC test for braking from 60 mph (100 kph) involved starting to brake as you pass a witches hat, and then measuring the distance covered to rest.

The test designed by smart people(German magazine AMS) starts braking at 110 kph. You then read off the distance covered from 100 kph to rest. This eliminates anticipation and buildup to max braking, and measures the effective tire and brake performance more accurately. The spread in results is much smaller. In the real world I agree that buildup does matter, when I'm back at work I'll have a look and see how significant that is (gut feel is not very)

Another example is the driveby test - the American test is far more realistic than the EEC one- you just drive along in D and floor the thing, no defined gear ratios, no silliness.

It would be wrong, irrespective of it's impact. As I noted, perhaps the standard needs to be addressed in your scenario if the result of being +\- 3% is negligible to the current 1%. It is like being dead or pregnant - you are or you are not - there are no half measures. It meets the spec or it doesn't.

If we decide that the spec is foolish and ignore it rather than address it, we are being dishonest. If we are willing to be dishonest about that, where do we draw no-longer-acceptably-dishonest line? I once had a customer "encourage" me to pad his insurance damage estimate so that he would get a larger payout on his motorcycle. I ignored it until he was so bold as to confront me on why I wasn't playing ball. My answer to him was simple - if I'm going to be dishonest with them and rip them off, what makes you think I won't be dishonest with you? He got the message.

Canuck- If everyone were as conscientious as you the world would be a much better place indeed. However, when it comes to enforcing government regulations/laws, things are not quite so black and white. Private companies and individuals have no choice when it comes to complying with laws/regulations. Government officials, on the other hand, are completely free to exercise their own discretion when it comes to enforcing their laws or regulations.

With regards to fuel consumption compliance tests, even a 1% variation can have a huge effect in theory. Consider that the US currently consumes around 134B gallons of gasoline per year.

Porsche have reputation of never exagerating the performance their cars can deliver so I would not imagine they are " cheats" in the EU CO2 test who taped over gaps etc and are thus " immoral" etc etc.

However they are clearly now engineers beyond the mere stunning - positively other worldly.

The government regulations regarding vehicle emissions or fuel consumption are meaningless in reality, since these standards are set arbitrarily. We should also remember that the auto companies have a far greater number of far more capable engineers designing their vehicles to pass these compliance tests, than the government has engineers writing the standards and regulations. Seriously, why does it matter if your new car only gets 25mpg/hwy instead of the published 26mpg/hwy?

And before any of you criticize the auto companies for taking full advantage of every regulatory "loophole", you should understand just how difficult it is to design an auto chassis and drivetrain capable of meeting modern fuel consumption, emissions and safety standards. A task made even more difficult by the incredibly high levels of reliability and performance that modern auto buyers now demand.

...absolutely correct, and it is a consumer (us), who pays for it, one way or another.

It would at least be an honest representation of what one might expect in real-world use.

Can't comment on cars, but two of my bikes have demonstrated fuel economy to within 0.1L/100km of the "official" numbers over about 82000km of well-varied road riding. I reckon that's pretty good. The third has had a few economy-affecting mods added (and removed) 51000km or so but is generally pretty close to the quoted figures. All three are Bavarian Money Wasters.

I did notice that two of my bikes are noticeably and reliably more frugal in hot weather. Sometimes a matter of an extra 50-70km range per tank refill. I'm not surprised at the difference, but quite surprised at the degree of difference. Max summer range in both cases is around 410km. Fuel refill is typically 15L or 21L, depending on which bike it is.

If every manufacturer cheats, does it really matter? Much like pro cycling?

If every manufacturer cheats, does it really matter? Much like pro cycling?

It wouldn't matter so much if they all cheated to the same degree, but how would you know? If FIAT told you that their 500 Multiair was good for 70mpg when it only did 43mpg, but Ford lied less and said their KA was good for 68mpg instead of its real 43mpg, how would you know who to mistrust the most?

My SEAT Ibiza TDi is meant to do 65mpg but the best I have ever seen is 62mpg when cruising on a motorway at 50mph. Overall, I get 50-55mpg.

It wouldn't matter so much if they all cheated to the same degree, but how would you know? If FIAT told you that their 500 Multiair was good for 70mpg when it only did 43mpg, but Ford lied less and said their KA was good for 68mpg instead of its real 43mpg, how would you know who to mistrust the most?

My SEAT Ibiza TDi is meant to do 65mpg but the best I have ever seen is 62mpg when cruising on a motorway at 50mph. Overall, I get 50-55mpg.

62mpg is pretty awesome for a vehicle with a kerb weight of about five times as much as my F650GS, I don't get any better than that with the F's wonderful Rotax. And the F is abnormally miserly for a bike of its capacity class. Hell, a friend's Honda CB400 Super Four (4cyl, ~400cc, VTEC shiny etc) never achieved better than 36mpg.

Does it degrade rapidly when you add passengers/cargo?

I found that another friend's Defender wagon (3.9L Isuzu NA diesel) never seemed to waver from 22mpg, whether loaded to the gills with boxes of books and pulling a trailer full of motorbikes when I moved interstate, or carrying nothing but myself and a spare tyre. 22mpg. At least it was predictable.

Maybe most bike manufacturers simply don't place economy very high on their priority list, preferring to spend their engineering dollars on trying to achieve a largely unusable 1MW/tonne. Some of them are getting rather worryingly close.

The constant reference to " cheating" when one car produces wider variations of real world versus test mpg is really a bit silly IMHO.

Both cars go throgh exactly the same test - one has better mpg than the other on that test cycle. If the gap is not related to real world differences then the test is an unrealistic one.

Governments specified the tests long ago, then they decided to use those test regimes to ESTIMATE average corporate fuel consumption/ CO2 per km. Then govenments made meeting a very strict minimum fuel consumption an effective condition of doing business for car companies.

The consequences are obvious and inevitable - mfrs. design to meet the rules imposed on them. Evidence from magazine testing suggets the test to real result gap is growing , witness the Fiat trend. That is exactly what would be predicted from the legistlative approach.

The new Porsche Panamera mentioned above is an extreme example which perfectly illustrates the real problem which is stupid legistlation.

No 410 bhp, 167 mph car is going to acheive 91 mpg in real life BUT I am pretty sure that if any owner drove it exactly acording to the test cycle it would indeed do 91 mpg.

I used to drive an MV 750 America and got plus or minus, depending on how I used the throttle, 40 mpg.

Driving into the worst rain storm I ever drove in, I got 42 mpg.

When comparing mileage between a M/C and car you would need to account for some significant differences. Most obviously, the M/C is not required to meet many of the safety requirements that auto must. The auto must have bumpers, seats that provide restraint of the occupant, windscreens, doors, etc. On the other hand, the auto may have less aero drag per person than the M/C. You alone on your M/C getting 42mpg would be equivalent to an auto with 4 occupants getting 10.5mpg.

When comparing mileage between a M/C and car you would need to account for some significant differences. Most obviously, the M/C is not required to meet many of the safety requirements that auto must. The auto must have bumpers, seats that provide restraint of the occupant, windscreens, doors, etc. On the other hand, the auto may have less aero drag per person than the M/C. You alone on your M/C getting 42mpg would be equivalent to an auto with 4 occupants getting 10.5mpg.

Bob Riebe- In your opinion, what part(s) of my post regarding comparisons between motorcycle and auto fuel mileage makes no sense? Does your motorcycle have seatbelts, bumpers, head restraints, doors, windshield wipers, or airbags? Or do you disagree that 4x10.5=42?

Bob Riebe- In your opinion, what part(s) of my post regarding comparisons between motorcycle and auto fuel mileage makes no sense? Does your motorcycle have seatbelts, bumpers, head restraints, doors, windshield wipers, or airbags? Or do you disagree that 4x10.5=42?

Total drag (in lbs) can be found by multipyling the Cd, dynamic pressure* (q), and the surface area (S). dynamic pressure is made up from the density ratio (local air density accounting for local altitude, temperature, and barometric pressure measured against standard density) multiplied by the air velocity in knots squared. The resultant of that is then divided by 295.

Dt=Cd(q)S

Drag is determined by five factors. Cd, surface area, local pressure, local temperature, and air speed.

Sports cars generally have Cd numbers in the mid 0.3s. Motorcycles have Cd numbers close to 1.0 depending on the model bike, size of rider, and riding position. Drag is increasing exponentially with speed.

Outside of nut-job Joan Claybrook, who was moronic enough to have rear-steer motorcycle built, why in God's green earth would any put any of those devices on a motorcycle.

Honda have been shipping Goldwings with airbags for a few years now. Too lazy to go hunting numbers, but with the 'Wing already being a fairly heavy bike the weight increase as a percentage of total mass would not be very large. As for why... there are already reports of people walking away essentially unhurt from fairly bad crashes. In at least one of those cases the rider wasn't wearing a helmet. Evolution was cruelly thwarted!

My K1200GT is not so much smaller than a 'Wing, but it is ~141kg lighter. I've observed only minimal increase (about 1.9%) in fuel consumption when carrying a passenger, which sort of makes sense if the aero is the big factor - a passenger sitting right behind me isn't going to increase aero drag very much. Tiina has indicated that if her helmet is right behind mine, she has no need of earplugs. Completely unscientific, of course.

In city riding this would also be affected by having a very different (smoother and slower) riding style when carrying a passenger, but on the highway stretches I observed roughly the same increase in fuel consumption when 2-up.

FWIW the 'Wings also have adjustable air vents for the rider. And a CD player, radio, satnav, and CB transceiver. And cruise control. They are gadget-laden.

Lots of BMW bikes these days have tyre pressure sensors+transmitters in the wheels, with the pressures being displayed on the dash. I wish all cars had this gadget! How many people do you know that check their tyre pressures every single time, without fail, ever, when they drive their car?

Sports cars generally have Cd numbers in the mid 0.3s. Motorcycles have Cd numbers close to 1.0 depending on the model bike, size of rider, and riding position. Drag is increasing exponentially with speed.

Where does that Cd for motorbikes come from? Research or plain guess?I searched a bit around and found some numbers. German magazine 'Motorrad' took a bunch of sportbikes and put them in a windtunnel to see what comes out.Those were the bikes used: Honda CBR 900 RR, MV Agusta F4 750 S/Oro/1+1, Suzuki GSX 1300 R Hayabusa, Suzuki GSX-R 750, Yamaha YZF-R1, Kawasaki ZX-12R.the Cd mentioned in the article went from 0.48 (Hayabusa w/ rider lying) to 0.56 (MV w/ rider sitting).

My K1200GT is not so much smaller than a 'Wing, but it is ~141kg lighter. I've observed only minimal increase (about 1.9%) in fuel consumption when carrying a passenger, which sort of makes sense if the aero is the big factor - a passenger sitting right behind me isn't going to increase aero drag very much. Tiina has indicated that if her helmet is right behind mine, she has no need of earplugs. Completely unscientific, of course.

In fact it could improve the drag number, by improving the fineness ratio. The contra-indication is that your fuel consumption increase is the same in both in-town and country riding, so I suspect the fineness ration is not improved enough.

Where does that Cd for motorbikes come from? Research or plain guess?I searched a bit around and found some numbers. German magazine 'Motorrad' took a bunch of sportbikes and put them in a windtunnel to see what comes out.Those were the bikes used: Honda CBR 900 RR, MV Agusta F4 750 S/Oro/1+1, Suzuki GSX 1300 R Hayabusa, Suzuki GSX-R 750, Yamaha YZF-R1, Kawasaki ZX-12R.the Cd mentioned in the article went from 0.48 (Hayabusa w/ rider lying) to 0.56 (MV w/ rider sitting).

BTW: the Ford Model-T had a Cd of 0.9 with the shape of a brick...

Of course, we all know the Cd needs to be multiplied by area to produce a total drag figure, and as a result the bike's total drag is still quite low (at least comapred to most cars).

- Higher aero drag as mentioned already.
- Compared to a car, overcoming road-loads is accomplished using a very small fraction of engine output which puts the engine in a lower efficiency region
- Motorcycle engines are designed for high specific output which necessitates efficiency tradeoffs.
- Emission reg's are looser for MCs in most jurisdictions. This may allow a less efficient tune.
- Lack of legislation to drive economy improvements
- Lack of consumer demand for better economy (fuel is not a major expense)

I did not claim that motorcycles have poor fuel consumption in simple terms. What I argued was that if the fuel consumption of a motorcycle was adjusted to compensate for factors that autos are subjected to, then their fuel consumption is not quite so great in comparison. For example, consider the BSFC of the best motorcycle engine versus the best auto engine. The best auto engine wins hands down.

Because fuel isn't a driving development factor in motorcycles - or hasn't been. Money goes into trying to get 4-strokes to perform like 2-strokes as the latter get legislated out, into trying to wring 200hp/l from the 900cc engine instead of just the 600cc version, of trying to get the 2100cc 700+ pound luxury barge to act like it's a sportbike in the twisties and a Newell motorcoach on the straights. No...fuel consumption in motorcycles gets only a passing reference.

Because fuel isn't a driving development factor in motorcycles - or hasn't been. Money goes into trying to get 4-strokes to perform like 2-strokes as the latter get legislated out, into trying to wring 200hp/l from the 900cc engine instead of just the 600cc version, of trying to get the 2100cc 700+ pound luxury barge to act like it's a sportbike in the twisties and a Newell motorcoach on the straights. No...fuel consumption in motorcycles gets only a passing reference.

We've come a long, long way since 2-strokes. I think the focus on fuel consumption will arrive. It may take the imposition of strict emissions laws to get there.

Few bikes are truly cheaper to operate than an economical car. And in some places (Australia) there are tax breaks available to car owners that are not available for motorcycle owners.

Reviving this thread on "cheating" in scare quotes to show a recent real-world result. Make no mistake, this is a big deal. In the sports world, bending the rules is called "cheating." In the business world, bending the rules could be a felony.

For those who don't know, Sam Winegarden is, make that was, the number one engine man at General Motors, big boss man. Among his positive achievements I believe he was one of the leading guys on the LS V8 program, CE or DRE. Also, he's a really nice guy--always was to me, anyway. This is a very sad way to end a career.

“Over a period of time some employees of the company engaged in the practice of identifying engines with lower emission which were fine-tuned and kept aside to be used for installation on vehicles during inspection.”

Who'da thunk it?

Just goes to show, the only sure way to obtain a representative vehicle for testing is to buy one from the showroom floor.

“Over a period of time some employees of the company engaged in the practice of identifying engines with lower emission which were fine-tuned and kept aside to be used for installation on vehicles during inspection.”

Who'da thunk it?

Just goes to show, the only sure way to obtain a representative vehicle for testing is to buy one from the showroom floor.

Let's say you are global VP of engines for a multinational auto manufacturer, and the CEO asks you, "Do our vehicles pass emissions?" If your answer requires more than 25 words, you might be doing it wrong.

Let's say you are global VP of engines for a multinational auto manufacturer, and the CEO asks you, "Do our vehicles pass emissions?" If your answer requires more than 25 words, you might be doing it wrong.

Sadly that isn't the question we are asked. The question is more usually, are you confident that by the time we hit Job 1 all possible variants of this model will pass emissions in the jurisdictions in which they are on sale?

So, given that you can't test every variant (300 powertrain/ mass combinations in a Transit at a rough guess) , and given that the software is in a state of flux, and that some of the hardware combinations have never existed except on paper, the answer often takes several reams of paper.

Sadly that isn't the question we are asked. The question is more usually, are you confident that by the time we hit Job 1 all possible variants of this model will pass emissions in the jurisdictions in which they are on sale?

So, given that you can't test every variant (300 powertrain/ mass combinations in a Transit at a rough guess) , and given that the software is in a state of flux, and that some of the hardware combinations have never existed except on paper, the answer often takes several reams of paper.

Sure, but none of that has anything to do with this issue. GM employees were caught red-handed in the wanton circumvention of the regulations. They were not caught in the act of beavering away in a sincere effort to meet the regs, as suggested above. Their plan was to get around all that, hmm. And I'm sure they invented a dozen rationalizations to justify their actions, which evaporated into thin air the moment they were caught.

All of this is fascinating--and I'm not being sarcastic or even ironic.

To me, real world fuel consumption is what I get out of my own vehicle the way I use it. I usually do a fuel check when i buy a car just out of curiosity. I did such a check on my 2+ tons of vintage Rolls-Royce some years ago and got around 15 miles per imperial gal around town, 17 cruising in the country, about what you'd expect from 6.3 litres and auto plus all the bells and whistles. I have no idea what the car would deliver on an official cycle. Don't care, either.

When I was riding a BMW 1 litre boxer bike some years ago I didn't check officially, so to speak, but I noticed that I had to refill with amazing frequency. On the 2,500 mile haul across Australia I guesstimate around 40-45 mpg at best. And I was cruising at around 110 km/h, with an occasional tweak to 140 (rarely--the sight of that rough tarmac streaming past below me worried me, and when I got airborne over a cattle grid I decided 100-110 was the better part of valor.)

My best trick was getting close to 26 mpg (imperial) out of a 1973 Australian Ford Fairlane with a 302 Cleveland and auto box, and only because I was in the middle of nowhere when I realised I was showing empty on the gauge. When I refuelled in Ceduna, the car took on two litres more than than the maximum tank capacity, so I was running on memory by the time I rolled into the service station. That figure, by the way was for the entire run from fill to fill, not just the last few hundred yards. I know, because I logged that trip in a notebook.

My current daily hack, a 4.0 litre Aussie Falcon six, is amazingly economical for such a big car, no doubt due to a tall top gear. At this state's legal limit of 110 km/h she's pulling a little over 2000 rpm. Of course, EFI, computers, tall ratios and a somewhat sleeker shape than the R-R all contribute mightily.

To be honest, I'm not the slightest bit interested in comparing "official" fuel consumption between cars when I buy. I know a big, heavy car with a big motor is going to be thirsty, and a small econobox not very thirsty, but the differences from car to car in the same class don't influence me in the least, because they really are irrelevant.

The adventure with the Fairlane above, which normally delivered around 17-18 mpg, shows that a carefully controlled foot on the loud pedal makes far more difference.

All of this is fascinating--and I'm not being sarcastic or even ironic.

To me, real world fuel consumption is what I get out of my own vehicle the way I use it. I usually do a fuel check when i buy a car just out of curiosity. I did such a check on my 2+ tons of vintage Rolls-Royce some years ago and got around 15 miles per imperial gal around town, 17 cruising in the country, about what you'd expect from 6.3 litres and auto plus all the bells and whistles. I have no idea what the car would deliver on an official cycle. Don't care, either.

For true full-size old vehicle that is truly wonderful mileage.

I would take that and all the advantages that come with a full-size car to a 30 mpg econo-box any day.

In Australia fuel--petrol--is around $1.50 a litre.If you drive 20,000km per year,the extra cost to you for fuel in driving a full-size car ,with a biggish engine over a small car,if you take real world comparison between 12 litres/100km combined for the big car city/country,and 8 litres/100 km ditto for the small car would be in the order of $1000.Ive always taken the big car option for room,comfort and driveability...what better way is there to spend $1000 if you enjoy road trips with friends or family?

My current daily hack, a 4.0 litre Aussie Falcon six, is amazingly economical for such a big car, no doubt due to a tall top gear. At this state's legal limit of 110 km/h she's pulling a little over 2000 rpm. Of course, EFI, computers, tall ratios and a somewhat sleeker shape than the R-R all contribute mightily.

A guy I used to pit crew for used a VT Commodore SS (LS1/6-speed manual) to tow his IPRANSW racecar. On the highway the VT would yield ~8L/100km unloaded, and with the trailer + racecar hooked up, around 15-16L/100km. Pretty good really for a tow-car with sparkplugs.

Of course the VT was total garbage in other areas. You could see the panel gaps change with your naked eye when the trailer was hooked up, even with the OEM heavy-duty towing kit, airbags to correctly adjust rear ride height, and a carefully balanced trailer. Sometimes the rear doors would pop open. Definitely not the right tool for the job.

"Ford Motor Co. is cutting the stated fuel-economy rating of its C-Max Hybrid car 8.5 percent to 43 mpg from 47 mpg -- a rare and costly move that Ford spent months feverishly working to avoid."

It's a pity I'm not at work (yes yet another two month round the world holiday) I'd love to find out who is going to get promoted above their Peter Principle level as a result of this. Hopefully they'll be put in charge of ashtrays. I doubt they'll get sacked, if you follow the rules even when the rules are stupid then that indicates an appropriate corporate management mindset. Barf.

A guy I used to pit crew for used a VT Commodore SS (LS1/6-speed manual) to tow his IPRANSW racecar. On the highway the VT would yield ~8L/100km unloaded, and with the trailer + racecar hooked up, around 15-16L/100km. Pretty good really for a tow-car with sparkplugs.

Of course the VT was total garbage in other areas. You could see the panel gaps change with your naked eye when the trailer was hooked up, even with the OEM heavy-duty towing kit, airbags to correctly adjust rear ride height, and a carefully balanced trailer. Sometimes the rear doors would pop open. Definitely not the right tool for the job.

Same bollocks some people have liked spreading since the first Holdens ever appeared.FJ Holdens were reputed to jam the back doors after pulling a caravan,that was drivel too.